Re: Decay watch: Iridium 19 Delta 2 rocket

Alan Pickup (alan@wingar.demon.co.uk)
Sat, 18 Apr 1998 11:51:49 +0100

This came down very much on schedule.

The final two published elsets ...

Iridm 19 Delta r 5.9  2.4  0.0  5.6 d            157 x 126 km
1 24970U 97056F   98107.84786196  .21619345  00000-0  21675-3 0  2867
2 24970  83.5758 263.2695 0023610 273.5478  86.3739 16.49304187 31879
Iridm 19 Delta r 5.9  2.4  0.0  5.6 d            148 x 116 km
1 24970U 97056F   98107.90846387  .25511065  00000-0  16025-3 0  2871
2 24970  83.5775 263.2069 0024630 272.9312  86.9791 16.52732595 31883

... show it 3.9 and 7.2 seconds late respectively on yesterday's "9280"
SatEvo prediction. One unusual aspect of this decay, if USSPACECOM's
values are correct, is the way in which the eccentricity held up during
the final day - I had expected the orbit to become much more circular
before re-entry.

My final analysis suggests that decay occurred southbound as it
approached Antarctica at about 22:48 UTC (April 17.95) near 67 deg S, 90
deg E, which is ~2,000 km SW of Cape Horn. In fact, the uncertainty is a
good few thousand km along track but it could not, in my opinion, have
survived into its next orbit which might have carried over California.

              --------------------------------------

Now for those other decaying rockets:

Ir 51 CZ-2C r   12.0  3.5  0.0  4.3 d            390 x 160 km
1 25264U 98018C   98108.25311672  .01746974 -14798-5  54286-3 0   721
2 25264  86.3693   1.5184 0173049  77.6891 284.3702 15.99911440  3694
I predict decay for April 23, though the current NASA 60d Decay Forecast
gives April 19.

Iridm 43 Delta r 5.9  2.4  0.0  5.6 d            308 x 205 km
1 25044U 97069F   98108.26194416  .00979140 -13868-5  86184-3 0  2204
2 25044  83.5309 347.8637 0077322 103.0464 257.9499 16.06605214 25016
My SatEvo prediction is for April 24, as against NASA's of April 19.

Also, don't forget:
DBS2 Centaur r   5.9  2.4  0.0  5.6 d            1233 x 133 km
1 23193U 94047B   98107.98441675  .08387199 -60641-5  85033-3 0  2635
2 23193  26.8146 275.2240 0778730  59.6066 307.2202 14.63110831 69642
Which both SatEvo and NASA predict will decay on April 23.

Alan
-- 
 Alan Pickup | COSPAR site 2707:   55d53m48.7s N   3d11m51.2s W    156m asl
 Edinburgh   | Home:      alan@wingar.demon.co.uk       +44 (0)131 477 9144
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